The present invention relates to an expanding shaft, and more particularly to an expanding shaft of the type which carries tubular supports on which strips of plastic, aluminum or paper films are wound or from which the strips are unwound.
More specifically, the invention represents an improvement over the construction as shown, for example, in U.S. Pat. Nos. 5,597,134 and 5,746,386, the disclosures of which are incorporated herein by reference.
Expanding shafts are typically used when slitting a wide web of material into discrete widths and rewinding it on cores which may be made of cardboard, plastic or metal and the like. The shaft carries core stops adapted to engage the side edges of the cores to properly space the cores in the correct position for rewinding. The two patents mentioned above provide mobile means mounted for radial movement within slots in the expanding shaft. Core stops are adjustably mounted for axial movement longitudinally of at least one of the mobile means to vary the spacing of the core stops longitudinally of the shaft as desired. Locking means is provided for locking the core stops in position axially of the mobile means and the shaft.
With the arrangement as shown in the two patents, the longitudinal position of the core stops relative to the shaft can be adjusted while the shaft is mounted on a slitter-rewinder machine. However, it takes a significant amount of labor and down time of the machine while such changes are made.
Therefore, there has been a need to provide a construction wherein the slit widths on a slitter-rewinder machine can be changed in a minimum amount of time. Rather than adjusting the core stops to a new width on the machine, operators have replaced the old mobile means and the core stops mounted thereon with a new mobile means which has a predetermined new spacing of the core stops thereon. The old mobile means may be replaced by a new mobile means in a minimum amount of time. The spacing on the new mobile means can be set by a machine operator while the old mobile means is in operation so that when the old mobile means is replaced by the new mobile means, down time of the machine is minimized.
Each mobile means is normally biased by springs radially inwardly of the shaft so that each mobile means is retracted into the shaft when the associated thrusting means is deactivated. The springs act between the shaft and the mobile means. When the mobile means and the core stops carried thereon are removed from the shaft, the springs are difficult to handle and are often lost. It therefore is a principal object of the invention to provide an arrangement whereby at least a portion of a mobile means on which core stops are mounted may be removed and replaced while the retracting springs remain in place within the shaft and are not subjected to any longitudinal forces during such removal and replacement.
A further problem arises in the prior art. When there is a slight change in web position, it is desirable to provide means for axially adjusting the support means and the core stops supported thereby while the support means is mounted in operative position within a slot in the expanding shaft. This has not been possible with prior art constructions.